This invention relates to a semiconductor read only memory (ROM) which can be more efficiently manufactured than conventional memories with higher productivity.
A conventional mask ROM (read only memory) is manufactured by the use of photo masks on which patterns are written corresponding to the desired data to be stored in the memory cells. First, the user presents a desired specification to the maker. The maker must then produce the logic design and pattern design, manufacture the mask and make the wafer later at the user's request. The maker could not start to manufacture the ROM until the specification of the user was finished.